In Marxist dependency theory, the uneven and combined development of productive forces across core and periphery is a key feature of capitalism. The unity of such sys- tematically differing components of the world economy is defined by the combination of borders and nation-wide productivity and labour remuneration standards. Periph- eral value spaces stand in a relationship of dependency with core value spaces, which provides the economic rational for the political domination of the latter over the former. The foundation of this dependency lies in the interaction between unequal exchange dynamic and the heightened exploitation of labour. Indeed, super-exploiting labour allow peripheral capitals to partially compensate for the value their are losing as a consequence of unequal exchange. For that reason, peripheral value spaces exhibit a fundamentally heteronomous and extroverted mode of development. This interaction takes place through the evolution of exchange rates, whose main functions is to verify the monetary character of the various currencies. Through the latter’s perpetual comparison, they reproduce the general equivalent whose existence is a structural necessity for any market-based economy, such is capitalism. Doing so, exchange rates formally mediate value spaces that nonetheless retain systematically diverging characteristics. However, on the one hand, Marxist dependency theory does not offer an unified exchange rate theory. On the other, within Marxist economic literature, while several attempts at expounding a model of exchange rate determination are to be found, they yield differing conclusions and more importantly were not integrated with the debates on dependency. This article proposes to revise differing Marxist understanding of the exchange rate, seeing the latter’s determination as key mechanisms leading to the reproduction of dependency. It thus discusses insights from Shaikh, Carchedi, Astarita and Ricci with the dependency tradition originating in Marini’s work. On this basis, we suggest that as they contributes to the verification of the socially acknowledged monetary character of the various currencies, exchange rates determine the magnitude of unequal exchange. Consequently, the latter is best seen not as a transfer of value but as a loss of value, in contrast with the traditional “phlogistic” understanding of unequal exchange that can be found in the literature on unequal ex- change, especially in Emmanuel’s writings. Finally, the point is to explore how the mediating role of exchange rate necessarily implies the super-exploitation of labour-power.